Behavioral activation by stimulation of a GABAergic mechanism in the preoptic area of rat.

The locomotor activity and grooming of conscious freely moving rats were recorded during a 60-min unilateral perfusion of the preoptic area with neuroactive compounds using the microdialysis technique. The GABA agonist, muscimol (10, 20 and 100 microM) induced a dose-dependent increase in locomotor activity and grooming which was attenuated by co-perfusion with the GABA antagonist, bicuculline (10 microM), and was blocked by systemic injection of haloperidol, a preferential dopamine D2 receptor antagonist (0.25 mg/kg). Muscimol-induced hyperactivity was associated with a simultaneous increase of striatal extracellular dopamine. These data suggest that the preoptic area is functionally linked with the extrapyramidal dopaminergic system possibly via GABAergic system.